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UNITED STATES ATENT OFFICE.

HOWARD W. MATHESON, OF WILMINGTON, DELAWARE, ASSIGNOR TO E. I. DU PONT DE NEMOURS AND COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE.

No Drawing.

T 0 all whom it may concern:

Be it known that I, HOWARD W. h/Lx'rrncsox, of lVilmington, in the county of New Castle, and in the State of Delaware, have invented a certain new and useful Improvement in Processes of- Fireproofing and Products Thereof, and .do hereby declare that the fol lowing is a full, clear, and exact description thereof.

My invention relates particularly to a process of rendering surfaces fireproof, and the product thereof.

. My invention relates more particularly, however, to the fireproofing of surfaces havinga coating of nitrocellulose.

l-Ieretofore, nitrocellulose has been used as the particular constituent in coatings for artificial leather, aeroplane wings, etc., where the properties of tensile strength, elasticity, and windproofing are desired. Other mate- 'rials cannot be successfully substituted pro vided with these. desirable qualities. One ob ect1on to the use of such coatings is, however, their inflammability. This is especially true in the case where such coatings are used on aeroplane wings, as aeroplane wings are so located as to frequently have sparks from the engine come into contact with the same. In view of this fact, attempts have been made to substitute other materials for nitrocellulose in such coatings. Cellulose acetate has, for example, been suge'sted for this purpose, but owing to the brittlenessof coatings produced with this material, this substitution for nitrocellulose has been without success. Various varnishes have also been tried, but these are not sufficiently fire-resistant to be of practical value in this connection.

The object of my invention is to provide a coating for surfaces which will not have the above disadvantages. I havefound if a thin coating of a condensation product of phenol and formaldehyde in a'suitable solvent is applied. to a surface to which a nitrocellulose coating has been appliechthe surface is rendered, inthis way, very resistant to ignition from sparks.

\Vhile my invention is capable of embodiment in many different forms, I shall describe only one form thereof herein.

' My invention may, for example, be carried out as follows: I

A. quantity of a condensation product of Specification of Letters Patent.

PROCESS OF FIREPROOFING AND PRODUCTS THEREOF.

Patented July 8, 1919.

Application filed December 13, 1915. Serial No. 6,463.

phenol and formaldehyde, as. for example,

bakelite condenslte etc. is dissolved m a suitable solvent, a solvent being preferably chosen, however, which is-also a solvent for nitrocellulose, so as to thereby obtain a coating' anchorage. In practice. the condensation product is preferably dissolved in a solvent of thesame, and to this is added a quantity of a solvent for both the condensation product and pyroxylin, suclnfor example, as acetone. ethyl acetate, amyl acetate, etc. The solution thus obtained is brushed over the inflammable surface containing pyroxylin, and when the solvents have evaporated there is left a tire-resistant film which cannot.

,Pyroxylin 6% Alcohol 20% Benzol LO /0 Ethyl acetate 3&70

This contracts the linen and draws it taut, and renders the material waterproof, windproof, etc. The wings are then given two coats of the following composition:

50 parts bakelite varnish containing solid bakelite, a condensation product of phenol and formaldehyde, dissolved in 25% alcohol and 20% benzol; 35 parts ethyl acetate; 1'5 parts of 100% benzol; 10 parts castor oil. In this composition, castor oil is not absolutely necessary, but isadvantageous as it imparts a certain amount of flexibility to the film, and instead other oils may be used, as, for example, rape seed oil, hnseed oil, corn oil, etc.

\Vhile I have described my invention above in detail, I wish it to'be understood that many changes may be made therein without departing from the spirit of my invention.

I claim:

1. The process of rendering a surface having a nitrocellulose coating fire-resistant which comprises applyin a coating of a condensation product of p enol and formaldehy'de.

2'. The process of rendering a surface having a nitrocellulose coating fireresistan t which comprises applying a coating of a lacquer of a condensation product of phenol and formaldehyde.

The process of rendering a surface-having a nitrocellulose coating fire-resistant which comprises applying a coating of a phenol and formal cellulose and the condensation product. 6. The process of renderlng a surface having .a nitrocellulose coating fire-resistant which comprises applying a coating of a lacquer of a condensation product of phenol and formaldehyde, the coating of the condensation product containing asolvent of the nitrocellulose and the condensation product.

1 7. The process of rendering a surface having a nitrocellulose coating fire-resistant which comprises applying a coating of a.

condensation product of phenol and formaldehyde, and an oil, the coating of the condensation product containing a solvent of the nitrocellulose and the condensation product. a

8. "The process of rendering a surface having. a. nitrocellulose coating fire-resistant which comprises applying a coating of a lacquer of a condensationproduct of phenol and formaldehyde and an oil, thecoating of the condensation product containing a sol-v vent of the nitrocellulose and the condensation product.

9. Ar covering comprising a coating of nitrocellulose and a condensation phenol-and formaldehyde.

10. A covering comprising a coating of nitrocellulose and a condensation product of phenol and formaldehyde, the condensation product comprising a separate layer cover ing the nitrocellulose;

11. A covering comprising a coating of nitrocellulose and a condensation product of.

phenol and formaldehyde, the condensation product containing a quantity of oil and comprising a separate layer covering the nitrocellulose.

In testimony that I claim the/ foregoing I I have hereunto set my hand.

Witnesses:

CHARLES E. ARNOLD, JOHN C, EMHARDT.

HOWARD W. MATHESON.

product of 

